British consumers are going off potatoes, in part because of an increasing taste for rice dishes and fajitas, new figures show. Sales of fresh potatoes slumped by more than 8% during the past year as shoppers opted for alternatives.

The trend is worrying the Potato Council, which represents growers and has warned that their crop faces a "fight for relevance" as shoppers switch to other staples, or buy smaller retail packs and smaller salad potatoes. It is urging retailers to take urgent steps to arrest the decline through recipes and in-store promotions that emphasise cooked meals rather than the raw ingredient.

Caroline Evans, head of marketing and corporate affairs at the Potato Council, told the Grocer magazine: "It's good that people are not actively rejecting the category. People still like potatoes, but the challenge is that we need different approaches for the whole supply chain.

"Shoppers need distractions and better signposting. A lot of shoppers make an emotional connection when they see a potato in its prepared form, rather than as a raw vegetable."

She said the growing popularity of curry and fajitas – and the national drive to reduce food waste – were also factors in the declining sales of fresh potatoes.

The volume of fresh potatoes sold fell by 8% over the year to May, according to data from Kantar Worldpanel, yet 90% of consumers who were buying less were not aware that they had cut back.

Total annual potato sales are worth £2.3bn a year, excluding crisps and snacks, with fresh potatoes accounting for £1.4bn. The retail potato market is dominated by the supermarkets, with the top five accounting for more than 77% of sales.

Fresh organic potatoes have fared particularly badly. Following a recovery in 2013, sales have declined again and in the last quarter reached one of the lowest volumes recorded since 2010. Tinned potatoes show continuing volume growth.